summaryrefslogtreecommitdiffstats
path: root/lib/raid6/recov_s390xc.c
diff options
context:
space:
mode:
Diffstat (limited to 'lib/raid6/recov_s390xc.c')
-rw-r--r--lib/raid6/recov_s390xc.c117
1 files changed, 117 insertions, 0 deletions
diff --git a/lib/raid6/recov_s390xc.c b/lib/raid6/recov_s390xc.c
new file mode 100644
index 000000000..179eec900
--- /dev/null
+++ b/lib/raid6/recov_s390xc.c
@@ -0,0 +1,117 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * RAID-6 data recovery in dual failure mode based on the XC instruction.
+ *
+ * Copyright IBM Corp. 2016
+ * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
+ */
+
+#include <linux/export.h>
+#include <linux/raid/pq.h>
+
+static inline void xor_block(u8 *p1, u8 *p2)
+{
+ typedef struct { u8 _[256]; } addrtype;
+
+ asm volatile(
+ " xc 0(256,%[p1]),0(%[p2])\n"
+ : "+m" (*(addrtype *) p1) : "m" (*(addrtype *) p2),
+ [p1] "a" (p1), [p2] "a" (p2) : "cc");
+}
+
+/* Recover two failed data blocks. */
+static void raid6_2data_recov_s390xc(int disks, size_t bytes, int faila,
+ int failb, void **ptrs)
+{
+ u8 *p, *q, *dp, *dq;
+ const u8 *pbmul; /* P multiplier table for B data */
+ const u8 *qmul; /* Q multiplier table (for both) */
+ int i;
+
+ p = (u8 *)ptrs[disks-2];
+ q = (u8 *)ptrs[disks-1];
+
+ /* Compute syndrome with zero for the missing data pages
+ Use the dead data pages as temporary storage for
+ delta p and delta q */
+ dp = (u8 *)ptrs[faila];
+ ptrs[faila] = (void *)raid6_empty_zero_page;
+ ptrs[disks-2] = dp;
+ dq = (u8 *)ptrs[failb];
+ ptrs[failb] = (void *)raid6_empty_zero_page;
+ ptrs[disks-1] = dq;
+
+ raid6_call.gen_syndrome(disks, bytes, ptrs);
+
+ /* Restore pointer table */
+ ptrs[faila] = dp;
+ ptrs[failb] = dq;
+ ptrs[disks-2] = p;
+ ptrs[disks-1] = q;
+
+ /* Now, pick the proper data tables */
+ pbmul = raid6_gfmul[raid6_gfexi[failb-faila]];
+ qmul = raid6_gfmul[raid6_gfinv[raid6_gfexp[faila]^raid6_gfexp[failb]]];
+
+ /* Now do it... */
+ while (bytes) {
+ xor_block(dp, p);
+ xor_block(dq, q);
+ for (i = 0; i < 256; i++)
+ dq[i] = pbmul[dp[i]] ^ qmul[dq[i]];
+ xor_block(dp, dq);
+ p += 256;
+ q += 256;
+ dp += 256;
+ dq += 256;
+ bytes -= 256;
+ }
+}
+
+/* Recover failure of one data block plus the P block */
+static void raid6_datap_recov_s390xc(int disks, size_t bytes, int faila,
+ void **ptrs)
+{
+ u8 *p, *q, *dq;
+ const u8 *qmul; /* Q multiplier table */
+ int i;
+
+ p = (u8 *)ptrs[disks-2];
+ q = (u8 *)ptrs[disks-1];
+
+ /* Compute syndrome with zero for the missing data page
+ Use the dead data page as temporary storage for delta q */
+ dq = (u8 *)ptrs[faila];
+ ptrs[faila] = (void *)raid6_empty_zero_page;
+ ptrs[disks-1] = dq;
+
+ raid6_call.gen_syndrome(disks, bytes, ptrs);
+
+ /* Restore pointer table */
+ ptrs[faila] = dq;
+ ptrs[disks-1] = q;
+
+ /* Now, pick the proper data tables */
+ qmul = raid6_gfmul[raid6_gfinv[raid6_gfexp[faila]]];
+
+ /* Now do it... */
+ while (bytes) {
+ xor_block(dq, q);
+ for (i = 0; i < 256; i++)
+ dq[i] = qmul[dq[i]];
+ xor_block(p, dq);
+ p += 256;
+ q += 256;
+ dq += 256;
+ bytes -= 256;
+ }
+}
+
+
+const struct raid6_recov_calls raid6_recov_s390xc = {
+ .data2 = raid6_2data_recov_s390xc,
+ .datap = raid6_datap_recov_s390xc,
+ .valid = NULL,
+ .name = "s390xc",
+ .priority = 1,
+};